Fūinjutsu (封印術; Literally meaning "Sealing Techniques") are a type of jutsu that seal objects, living beings, chakra, along with a wide variety of other things within another object. Fūinjutsu can also be used to unseal objects either from within something or someone.

Trivia

An imbalance is created when an odd-numbered seal is placed on top of an even-numbered seal and vice-versa. This can be used offensively, as when Orochimaru uses the Five Elements Seal to seal off Naruto's access to the Kyuubi chakra. [1]

The shinobi from Uzushiogakure in the Land of Whirlpools were specialists in the art of fūinjutsu, to the point that their nation was eventually destroyed due to the fear others had of these techniques.[2]